Large Proper Motions in the Jet of the High‐Mass YSO Cepheus A HW2

Curiel, S.; Ho, Paul T. P.; Patel, Nimesh; Torrelles, J. M.; Rodrı́guez, Luis F.; Trinidad, M. A.; Cantó, J.; Hernández, L. A.; Gómez, José F.; Garay, Guido; Anglada, Guillem

doi:10.1086/498931

Cited by 128 publications

(219 citation statements)

References 37 publications

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“…This would be about 100 times brighter than typical low-mass protostars at that distance. Also associated with HW2 is a "biconical thermal radio jet" at the size scale of ≃1 ′′ (≃725 AU), with the ionized gas exhibiting proper motions with velocities ≥ 500 km s −1 along the axis of the jet 14,19,20 . In addition, we estimate that the luminosity of the masers associated with Table 1.…”

Section: -2 -mentioning

confidence: 99%

A disk of dust and molecular gas around a high-mass protostar

Patel

Curiel

Sridharan

et al. 2005

Nature

199

221

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The processes leading to the birth of low-mass stars such as our Sun have been well studied, but the formation of high-mass (> 8 x Sun's mass) stars has heretofore remained poorly understood. Recent observational studies suggest that high-mass stars may form in essentially the same way as low-mass stars, namely via an accretion process, instead of via merging of several low-mass (< 8 Msun) stars. However, there is as yet no conclusive evidence. Here, we report the discovery of a flattened disk-like structure observed at submillimeter wavelengths, centered on a massive 15 Msun protostar in the Cepheus-A region. The disk, with a radius of about 330 astronomical units (AU) and a mass of 1 to 8 Msun, is detected in dust continuum as well as in molecular line emission. Its perpendicular orientation to, and spatial coincidence with the central embedded powerful bipolar radio jet, provides the best evidence yet that massive stars form via disk accretion in direct analogy to the formation of low-mass stars

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Section: -2 -mentioning

confidence: 99%

A disk of dust and molecular gas around a high-mass protostar

Patel

Curiel

Sridharan

et al. 2005

Nature

199

221

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“…The gas shows signs of rotation and is perpendicular to the highvelocity outflow (∼500 km s −1 ) seen in the radio continuum (Curiel et al 2006). The molecular outflow that we observe in methanol is blueshifted to the NE, which implies that this side of the outflow is pointing towards the observer, Fig.…”

Section: Outflow Morphologymentioning

confidence: 52%

“…The object shows both large-scale molecular outflows over ∼1 (Gómez et al 1999) and signs of collapse over a similar extent (Bottinelli & Williams 2004;Sun & Gao 2009). At the core of HW2, a thermal jet extends over ∼2 and proper motion outflow velocities of ∼500 km s −1 have been measured in the radio (Hughes & Wouterloot 1984;Curiel et al 2006). Although a superposition of gas components at different positions cannot be completely ruled out (Brogan et al 2007;Comito et al 2007), the evidence is building that there is a disk at the centre of the jet, which is observable in both molecular gas and dust (Patel et al 2005;Torrelles et al 2007;Jiménez-Serra et al 2007), as argued in detail in Jiménez-Serra et al (2009).…”

Section: Introductionmentioning

confidence: 83%

Distribution and excitation of thermal methanol in 6.7 GHz maser bearing star-forming regions

Torstensson

Tak

Langevelde

et al. 2011

A&A

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Context. Candidate high-mass star-forming regions can be identified through the occurrence of 6.7 GHz methanol masers. In these sources the methanol abundance of the gas must be enhanced, because the masers require a considerable methanol path length. The place and time of origin of this enhancement is not well known. Similarly, it is debated in which of the physical components of the high-mass star-forming region the masers are located. Aims. The aim of this study is to investigate the distribution and excitation of the methanol gas around Cep A and to describe the physical conditions of the region. In addition the large-scale abundance distribution is determined to understand the morphology and kinematics of star-forming regions in which methanol masers occur. Methods. The spatial distribution of methanol is studied by mapping the line emission, as well as the column density and excitation temperature, which are estimated using rotation diagrams. For a limited number of positions the parameters are checked with non-LTE models. Furthermore, the distribution of the methanol abundance is derived in comparison with archival dust continuum maps. Results. Methanol is detected over a 0.3 × 0.15 pc area centred on the Cep A HW2 source and shows an outflow signature. Most of the gas can be characterized by a moderately warm rotation temperature (30−60 K). At the central position two velocity components are detected with different excitation characteristics, the first related to the large-scale outflow. The second component, uniquely detected at the central location, is probably associated with the maser emission on much smaller scales of 2 . A detailed analysis reveals that the highest densities and temperatures occur for these inner components. In the inner region the dust and gas are shown to have different physical parameters. Conclusions. Abundances of methanol in the range 10 −9 −10 −7 are inferred, with the abundance peaking at the maser position. The geometry of the large-scale methanol is in accordance with previous determinations of the Cep A geometry, in particular those from methanol masers. The dynamical and chemical time-scales are consistent with a scenario where the methanol originates in a single driving source associated with the HW2 object and the masers in its equatorial region.

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“…This source is usually refered to as the center of the Cep A region. A thermal radio-jet with a position angle of ∼45 • is present (Curiel et al 2006), indicated by arrows in Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, Garay et al (1996) proposed that HW 3d drives an outflow directed towards HW 7, which is interpreted as shock induced radio emission. From their proper motion measurements of the individual components of HW 7, Curiel et al (2006) propose that the driving source is located just north of the HW 7a component, mainly because HW 7a moves almost perpendicularly to the rest of the HW 7 sources due south. We identify this source with GPFW 2 (Goetz et al 1998).…”

Section: Introductionmentioning

confidence: 99%

The Chandra X-ray view of the power sources in Cepheus A

Schneider

Günther

Schmitt

2009

A&A

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The central part of the massive star-forming region Cepheus A contains several radio sources which indicates multiple outflow phenomena, yet the driving sources of the individual outflows have not been identified. We present a high-resolution Chandra observation of this region that shows the presence of bright X-ray sources with luminosities of L X 10 30 erg s −1 , consistent with active pre-main sequence stars, while the strong absorption hampers the detection of less luminous objects. A new source has been discovered located on the line connecting H 2 emission regions at the eastern and western parts of Cepheus A. This source could be the driving source of HH 168. We present a scenario relating the observed X-ray and radio emission.

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Large Proper Motions in the Jet of the High‐Mass YSO Cepheus A HW2

Cited by 128 publications

References 37 publications

A disk of dust and molecular gas around a high-mass protostar

A disk of dust and molecular gas around a high-mass protostar

Distribution and excitation of thermal methanol in 6.7 GHz maser bearing star-forming regions

The Chandra X-ray view of the power sources in Cepheus A

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